Police are investigating the death of a woman who was reported missing last month and whose body was found in an apartment this week in the Pilsen neighborhood, according to police.

A missing person's alert had been issued last month for Michelle Manalansan, 29, who was last seen on Feb. 9 at her apartment on the 300 block of East South Water Street in the Near East Side neighorhood, according to police.

On March 17, police were called to the 1400 block of West Cullerton Avenue shortly before 9 a.m. after neighbors in the building at that location reported a strong odor, said Chicago Police News Affairs Officer Daniel O'Brien.

According to a police report, the woman's body was found decomposed in a plastic air mattress that had been slit open. She was found in the mattress along with garbage, according to the report.

According to the Cook County medical examiner's office and police, investigators initially were unable to identify the body because it had begun to decompose.

An autopsy was performed on Monday and the results were inconclusive. Officials said the cause of death was pending further investigation.

The missing person alert described Manalansan as 5 feet 3 inches tall, weighing 115 pounds, and said she was last seen wearing a pink jogging suit and white gym shoes. She was a student at Harold Washington College who frequented the downtown area, according to the police alert.